Hearing aid



Feb. 3, 1970 Filed March 10, 1967 F. J. STORK HEARING AID 5 Sheets-Sheet l Feb. 3, 1970 Filed March 10, 1967 F. J. STORK HEARING AID 3 Sheets-Sheet 2 cp.s.xl0

55 @WnwM Feb. 3, 1970' I F. J. STORK 3,493,695

HEARING AID Filed March 10. 1967 5 Sheets-Sheet s United States Patent 3,493,695 HEARING AID Fredrick J. Stork, 135 Hickson Drive, Kitchener, Ontario, Canada Filed Mar. 10, 1967, Ser. No. 622,116 Int. Cl. H04r 25/02 U.S. Cl. 179-107 6 Claims ABSTRACT OF THE DISCLOSURE A hearing aid incorporating rechargeable batteries, and wherein a polarized connector is used between a recharger and the batteries. The polarized connector comprises three equi-spaced male prongs, and three matching female receptors. One polarity is applied to the center prong and receptor, and the other to both of the outer prongs and receptors, whereby the connection will be properly polarized without heed to orientation of the male and female connector members.

This invention relates to battery powered hearing aid instruments, and particularly, but not exclusively, to hearing aids of the behind-the-ear type and the eyeglass type. Such hearing aids often have a sufiiciently low current drain as to permit the use of in-situ rechargeable nickel-cadmium batteries usable for a substantial part of a whole day. For example, sixteen hours use during the day and eight hours charging overnight. The invention further relates to a novel presentation case for storing the hearing aid when not in use, which case includes a charging apparatus for the battery and which incorporates a plug-and-socket connection having provisions for preventing improper assembly in the hands of aged or afflicted persons.

Hearing aid instruments, both of the in-the-ear and behind-the-ear, have been known to utilize rechargeable batteries. Unfortunately, however, the current consumption with such prior known instruments necessitated the user charging the batteries several times a day. This inconvenience stemmed from the fact that prior known instruments consumed two to four milliamperes. Such typical current values limited the use of such hearing aids to approximately four to seven hours. Both dealers and the public had become skeptical of hearing aids requiring such frequent changes of batteries. However, the greatest single disadvantage of prior known hearing aids existed in the fact that although batteries of the rechargeable type have been used therewith such practice has not enjoyed the convenience of in-situ recharging. That is, recharging of the battery while still installed in the hearing aid instrument. Further, in spite of the fact that prior known instruments have required frequent battery changes, access to the battery has frequently been awk- -ward often requiring unscrewing a cap of fiddling dimensions and sometimes requiring the use of a wrench or screwdriver. Again, it has been customary to provide a hearing aid as a single unit and to offer separately a recharging device, if the batteries incorporated have been of the rechargeable type. Such recharging devices have been of universal application designs permitting use with any rechargeable battery of similar capacity isolated from the equipment in which the battery is used. However, the availability of such recharging units has not overcome 3,493,695 Patented Feb. 3, 1970 the basic desirability of the in-situ battery recharging for hearing aid instruments. Again, in prior known hearing aid instruments of all types, there has frequently existed the necessity to provide plug and socket connectors. Such connectors were used between a microphone and an amplifier and/ or between an amplifier and the earphone. The connectors were of the polarized or non-polarized type. Where of the polarized two-pin type, the connectors invariably used a pair of plugs having diameters differing between each of the two plugs. It was found that aged and afflicted persons frequently attempted to force the two pins plugs, in reverse positions, into the associated socket invariably resulting in mal-functioning of the electrical operation of the units and the fracturing of the plugs and/or sockets.

In developing the hearing aid instrument in accordance with this invention all of the above-mentioned disadvantages have been overcome. Further, whilst developing an amplifier circuit having the necessary low current consumption, opportunity was taken to investigate desirable audio frequency spectra for hearing aid instruments and the circuit, herein to be disclosed, is found to have improved audio characteristics.

It is an aspect of one feature of the invention to provide a battery operated hearing aid circuit having a low current consumption and enhanced frequency spectrum.

In accordance with the foregoing aspect of the invention, the circuit comprises a positive power line, a negative power line connected to a source of direct current EMF, at least two stages each stage of which includes a silicon planar PNP transistor, the emitters of which transistors are connected to said positive line, the collector of the last stage transistor being connected to the negative line through an output load and the base of the same transistor being joined to the negative line through an associated base resistance, the collectors of transistors, excluding the last stage, being connected to the negative line through an associated load resistances, the bases and collectors of the transistors, excluding the last stage transistor, being joined by bias resistances, and the base of each transistors excluding the first stage transistor being capacitive coupled the collector of the preceding stage transistor, means for applying an input signal requiring amplification to the base of the first stage transistor through a capacitance.

It is an aspect of another feature of the invention to provide a polarized electrical contact of particular utility for use on hearing aid instrument body.

In accordance with this other aspect of the invention, there is provided contacts included with said body member are three in number, are of substantially identical dimensions and equally spaced apart on a straight line, the outer of said contacts included with said body member having like polarity and the centre of the contacts having opposite polarity.

It is an aspect of yet another feature of the invention to provide a presentation case for a portable electrical device containing a rechargeable battery and electrical contact means on said device to which a current may be applied for recharging of the battery while the latter is still contained within said device.

In accordance with the last mentioned aspect of the invention, the presentation case comprises: a bottom part including a first portion for receiving and protecting said device when the latter is not in use, a second portion including an electrical unit for providing a recharging current output and having an output cord through into said first portion, said first portion, said output cord being terminated with contact elements for selective cooperation with said electrical contact means on said device, a third portion for receiving a bunched-up electrical mains cord having a free end terminated with a plug cap, the other end of said mains cords being passed into said second portion and connected therein to said electrical unit, and, a lid for said bottom part.

It is an aspect of yet another feature of the invention to provide an easy access lid for a miniature battery compartment.

In accordance with the last mentioned aspect of the invention, there is provided a hearing aid instrument including an integral case housing at least an amplifying circuit and a battery compartment having a lid receiving recess therein and a removable lid for reception in said recess, the improvement comprising providing relative resiliency between the said recess in the case and said lid for frictionally retaining said lid in said recess.

A preferred embodiment of the invention will now be described with reference to the accompanying drawings in which:

FIG. 1 is a pictorial view of a hearing aid instrument having a three-pin socket for the reception of the threepin plug also shown.

FIG. 2 is a pictorial view of a presentation case for a hearing aid instrument, which case includes separate compartments for the instrument, for a charging unit, and for a mains cord.

FIG. 3 is a circuit diagram for a low current drain amplifier having enhanced audio characteristics.

FIG. 4 is a circuit diagram showing alternative switching arrangements for the circuit shown in FIG. 3.

FIG. 5A-5C are frequency response diagrams for the hearing aid circuit shown in FIG. 3 having a three-position tone control corresponding to low, normal and high pitch operation.

FIG. 6 is a circuit diagram of a charging unit.

FIG. 7 shows the novel manner in which the battery compartment lid is removed.

FIG. 8 is an exploded view of part of the hearing aid instrument and battery assembly.

It is to be understood that behind-the-ear hearing aid instruments in the following disclosure refers to the type supported by the ear alone or in combination with a bow temple member and wherein the entire instrument is worn immediately adjacent the ear of the user.

Referring now to FIG. 1 there is shown a pictorial view of a temple bow type hearing aid instrument generally indicated at 1. The instrument includes a microphone and receiver, not shown, which are positioned with the instrument in a well known manner and as such form no part of the present invention. The body of the instrument is formed in high impact scuff resisting Cycolac (trademarked copolymerised acrylonitrile styrene butadiene thermoplastics). Also shown is an On-Off switch S1, volume control (R4), lid 11 for a compartment for housing a nickel-cadmium battery and a three-pole receptacle 12 for the reception of a charge cord plug 13. As will be described hereinafter, switch S1 or volume control (R4) may be ganged to a multiple position tone control switch, alternatively either of the first two-mentioned items may be ganged to a telephone pickup control switch. Novel means for removal of the lid 11 will be described with reference to FIGS. 7 and 8.

While in the preferred embodiment use has been made of a nickel-cadmium battery, it is envisaged that other miniature batteries having a suitable discharge current rating and relatively long discharge periods are contemplated. Nickel-cadmium batteries have a sufficiently noisefree output to render the use of filters unnecessary. It is preferred that alternative batteries contemplated exhibit the same desi able noise-tree cha acteris i s,

Referring to FIG. 2 there is shown a presentation case 20, having three compartments therein. Compartment 21 is adapted to receive the hearing aid instrument 1, compartment 22 contains a charger unit whose output is available at plug 13 terminating a charge cord 14 and compartment 23 houses a line cord 24 one end of which is permanently connected to the aforementioned unit in compartment 22. The other end of the line cord 24 is fitted with a standard plug-in cap. The charger unit incorporates an ON-OFF switch S3 and an ON warning neon lamp NI.

Referring now to FIG. 3 there is shown an amplifier circuit for use in the hearing aid instrument.

Input to the amplifier is obtained either from a telephone pickup coil TE or a microphone M according to the position of a combined ON-OFF and mode selection switch S1. The switch SI is shown in the OFF position. Moving the switch anticlockwise by one contact space energizes the transistors and the coil TE. Moving the switch anticlockwise by another contact space isolates the coil TE, retains energization of the transistors and also powers a microphone M. The coil TE, the microphone M and all the associated circuit shown in FIG. 3 are housed within the hearing aid instrument which may be condensation sealed thereafter. The hearing aid instrument is specially equipped to provide isolation and feedback free suspension of the microphone and receiver.

The signal from the coil TE or the microphone M is capacitive coupled, by C1, to the base of a transistor T1 whose emitter is joined to the positive line and whose collector is joined to the negative line by resistance R2. Fixed bias is provided by a resistance R1. Items C1, T1, R1 and R2 comprise a first stage. A second and similar stage is comprised by capacitance C2, transistor T2, resistances R3 and R4 where R4 is variable to provide volume control. A third stage comprises capacitance C3, transistor T3, a current limiting resistance R5, and an earphone or receiver RE forming the output load, connected into the collector circuit of T3.

The transistors are all of the silicon planar PNP type having high amplification and lower current drain thus giving an overall reduction in current consumption.

A capacitance C4 is permanently connected between the collector of T3 and the positive line.

Tone control switch S2 and capacitances C5 and C6 comprise a tone-control feature shown dotted at TC which together with capacitance C4 permit three ranges of frequency response. It is to be understood that switch S2 may be arranged to effect parallel connection of either or all of capacitances C4C6.

It should be noted that coil TE and tone control TC are desirable features but not essential to the operation of the circuit. Again, while three stages of amplification are shown it will be understood that the previously identified first stage may be dispensed with if less amplification is acceptable. If the coil TE is dispensed with the connections to switch S1 will be as shown in FIG. 4. While the circuit shown indicates the use of an energized microphone or telephone pickup, it is to be understood that self-energized devices may be used in lieu thereof.

It is to be understood that rectifying means may be incorporated between battery and sockets 12 in order that an unrectified recharging input be applied to the instrument.

Appendix A lists the various components used in the above-discussed circuit. The said circuit has been found to exhibit enhanced audio characteristics although the precise explanation of the performance is speculative. Nevertheless the compression effect inherently desired in the hearing aid instrument art is superior than previously attained. This is due to the improved sound compression attainable by the configuration of the A.V.C. utilized in the above discussed circuit. The overall frequency response is approximately 2005000 c.p.s. The sound reproduced to the user s of ex p on l cla i y, here is substantially no back-ground noise and relatively complete suppression of sudden loud noises. The peak gain is comparable to previously known hearing aid instruments having a higher current consumption, i.e. 52-55 db. (See discussion of FIGS. 5A5C.) The current drain exhibited is approximately 0.81.0 ma.

As stated hereinbefore the battery B in the circuit is of the nickel-cadmium type, and when energizing the aforementioned circuit provides for about sixteen hours of continuous operation, during the day for example, and eight hours for complete recharging during the night. Thus, it is not necessary to remove the battery from the instrument during the useful life of the former. The life of such batteries is up to 6000 hours (approximately 1824 months). During this life the battery may receive about 600 charge and discharge cycles.

Referring now to FIGS. 5A5C there is shown frequency response curves when the hearing aid is operated in Low, Normal and High Pitch switch positions. In Low Pitch operation (FIG. 5A) it will be seen that the response peaks to about 45 db at approximately 1250 c.p.s. In Normal Pitch operation (FIG. 5B) the response has a predominant peak of 45 db at 1250 c.p.s. and secondary peak of 42 db at 2800 c.p.s. In High Pitch operation (FIG. 5C) the response peaks to about 45 db at 2700 c.p.s. It is believed that the three ranges of operation will provide for most hearing deficiencies encountered.

Referring now to FIG. 6, there is shown the charger unit located in compartment 22 shown in FIG. 2.

The charger is supplied via a line cord CO1 which feeds the primary winding of transformer T1 through a conventional resistive network R1, R2 and R3. An On warning neon lamp N1 with its associated dropping resistor R4 is also provided. The secondary of transformer T1 feeds a conventional full-wave diode bridge Whose rectified output is fed to a three conductor charge cord CO2 and three pin plug, 13, the latter been matched with socket 12, in the hearing aid instrument 1. A list of components used in the charger unit of FIG. 6 is shown in Appendix B. It is to be understood that the rectifying means and polarized plug may be dispensed with if the hearing aid incorporates integral rectifying means. The three-pin plug 13 and socket 12 forms an important aspect of the present invention. The three pins are disposed along a straight and the outer pins are symmetrically disposed each side of the centre pin. The pins are of substantially identical dimensions. Similarly, the sockets 12 included with the body member 1 are of similar spatial disposition as the pins on plug 13.

It will be seen in FIG. 6 that the two outer pins on plug 13 have like polarity while the centre pin is of 0pposite polarity. While the present embodiment indicates the outer pins as being of negative polarity and the centre of positive polarity, the polarities on the plug pins may, of course, be reversed provided that the outer pins are of the same polarity and appropriate reversing is effected on the socket 12. It will be appreciated that no matter which way round the plug 13 is inserted into the socket 12 correct polar connection will be achieved. By this means the dimensions and appearance of the pins can be identical and connected easily effected by aged or afflicted persons. It should be understood that while the body 1 is indicated as including the female or socket side of the connection and the male side or plug terminates the associated charges cord CO2, the male and female elements may be interchanged.

Referring now to FIG. 7 there is shown a simple means for removing the battery compartment cap 11. As mentioned, hereinbefore, the hearing aid instrument body 1 is formed of high impact scufi resistent Cyclolac. This material is mildly resilient permitting the battery compartment lid 11 to be frictionally retained in a suitably dimensioned recess in the battery compartment. To remove the lid 11 it is only necessary to pry up the lid by means of a pointed instrument 15 preferably inserted at a marked spot 16 adjacent the recess and on the surface of the instrument.

FIG. 8 is an exploded view of a portion of the instrument 1, the battery 11 with its associated leads, and a suitable spongy plug 11a to prevent rattling of the battery. To change the battery B it is only necessary to unsolder the associated leads from the old battery and to resolder the leads onto the replacement battery. Proper polarity must be observed in the usual manner. Attention is drawn to the fact that it is not necessary to take apart the hearing aid instrument in order to effect changing of the battery. While it is envisaged that the user will not normally change the battery, it will be appreciated that the simplicity of the operation will enable the operation to be accomplished with such common domestic equipment as a soldering iron. For those incapable of, or without equipment for changing the battery, the facilities of a service depot must be sought.

The preferred embodiments of the invention has been illustrated by a temple bow type hearing aid instrument wherein the receiver is integral with the remaining components. It is however, envisaged that the receiver may be a separative unit for in-the-ear application.

Thus, there has been disclosed a novel hearing aid instrument having enhanced acoustic performance, particularly low current consumption, provisions for in-situ recharging of batteries, a novel presentation case, an easy access lid to the battery compartment, and a fool-proof plug and socket connector for use therewith.

While the preferred embodiment of the invention has been described, it is to be understood that other embodiments falling within the terms of the appended claims are contemplated.

APPENDIX A Description of components R l50K ohm. R 4.7K ohm. R 330K ohm.

R l50300K ohm (current limiting), subminiature deposited carbon resistors, Siegert Type RKL10. R 12K ohm potentiometer, Wilbrecht Electronics Model 170, Log. Taper .1 w.

C C 2.2 mfd., 4 v. DC. +4020%, Model HP225R.

C C C .1 mfd., 20 v. DC. +4020%, Model HQ104R.

C .22 mfd., 15 v. DC. +40-20%, Model HQ224R, Components, Incorporated, Minitan H-Series, solid tantalum capacitor.

T T T National Semiconductor, Model NS6065,

silicone planar transistors, PN P.

M-Microphone, Model BE-1530.

RReceiver, Model BC-1524, Knowles Electronics, Inc.

TETelephone coil, (induction pickup coil).

S On-Off telephone switch, Model 2030-26.

S Tone switch, Model 2030-25, Danavox Internanational.

PONickel cadminum accumulator, Model DK-20,

DEAC (German Edison Co.), 20 mah. capacity.

APPENDIX B Part No.

Symbol i z R3 1 Description Resistor 12K 1W Resistor 2.7 k. M w.

N1 Neon indicator bulb .I. 001 Line cord complete C07 Three conductor charge cord complete 1 Due to differences in diodes R has to be selected to give 2.5 MA charge current at v. line voltage.

I claim:

1. In a hearing aid of the type wherein the entire instrument is disposed adjacent the ear region of the wearer and having an earphone receiver, an integral earpiece body member including a microphone, amplifier and battery, the improvement comprising polarised electrical contact elements included with said body respective poles of which elements are electrically connected to opposite poles of said battery, said polarised electrical contact elements being electrically connectable to associated polarised contacts forming the termination of a battery re-charging means.

2. Apparatus in accordance with claim 1 wherein said contacts included with said body member are three in number, are of substantially identical dimensions and equally spaced apart on a straight line, the outer of said contacts included with said body member having like polarity and the centre of the contacts having opposite polarity.

3. Apparatus in accordance with claim 2 wherein said outer contacts are of negative polarity and the centre of said contacts is of positive polarity.

4. In a hearing aid instrument having an earphone reeciver, an integral earpiece body member including a microphone, amplifier and battery, the improvement comprising polarised electrical contact elements included with said body respective poles'of which elements are electrically connected to opposite poles of said battery, said polarised electrical contact elements being electrically connectable to associated polarised contacts forming the termination of a battery recharging means.

' 5. The hearing aid improvement of claim 1 wherein said associated polarized contacts form the termination of a battery recharging feed cord.

6. The hearing aid of claim 4 wherein said associated polarized contacts form the termination of a battery recharging feed cord.

References Cited UNITED STATES PATENTS 3,327,070 6/1967 Renwick 179107 FOREIGN PATENTS 801,742 1936 France.

RALPH D. BLAKESLEE, Primary Examiner US. Cl. X.R. 

